Marie Yovanovitch is testifying this morning about being recalled from her post as ambassador to Ukraine and the subsequent revelation of the president’s hostility towards her in the White House’s summary of the July 25 Zelensky call. While she was testifying, Trump started attacking her on Twitter:

Everywhere Marie Yovanovitch went turned bad. She started off in Somalia, how did that go? Then fast forward to Ukraine, where the new Ukrainian President spoke unfavorably about her in my second phone call with him. It is a U.S. President’s absolute right to appoint ambassadors.

— Donald J. Trump (@realDonaldTrump) November 15, 2019

The president’s public and personal attack on a member of the Foreign Service is contemptible and unprecedented. Going after a career diplomat like this reflects not only the president’s usual disdain for our diplomats, but it shows his willingness to target and threaten public servants in the pursuit of his own personal interest. He abused his power by removing Yovanovitch, and he removed her because she was an obstacle to the shadow foreign policy that was being used to advance the president’s personal interests.

The content of the attack is predictably nonsensical. U.S. diplomats are not responsible for the conditions in the country where they serve, and in any case the most difficult assignments are typically given to the best Foreign Service Officers. The fact that Yovanovitch was given hard assignments is a testament to her qualifications. Zelensky was going along with whatever Trump said because he wanted to stay on Trump’s good side. When Trump declared that Yovanovitch was “bad news,” Zelensky hastened to agree with him because he didn’t want to make him angry. Trump does have the right to recall an ambassador, but the reason why he recalled this one underscores that his motives were bad, self-serving ones.

Now he is publicly attacking a witness in the impeachment inquiry, which almost certainly exposes him to new charges of illegal conduct. When someone as powerful as the president publicly goes after a witness, it is bound to have an intimidating effect on her and other witnesses. Trump has responded to an investigation into his abuse of power by committing more abuses that make impeachment that much more likely and necessary.